Browsing by Author "Kostekci, Sedat"

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Alkaline Cellulase Free Xylanase From Bacillus Sp. Asx42: Properties, Purification and Its Effect on Seed Germination
(Slovak Univ Agriculture Nitra, 2022) Kostekci, Sedat; Aygan, Ashabil; Comlekcioglu, Nazan; Sariturk, Sevtap
Bacillus sp. ASX42 isolated from soil samples of Lake Van shores, Turkey, and the strain producing cellulose-free xylanase enzyme with an optimum pH 9.0, at 60 degrees C. The molecular weight of the enzyme was estimated as 66 kDa on SDS PAGE analysis. Thermal stability of enzyme was detected average 68.7% at 4-60 degrees C and 60% at 65-95 degrees C while pH stability was observed about 90% between pH 3.5-13.0 for 15 min. As HgCl2 presented a strong inhibitor activity, Cobalt (132%) and Manganese (130%) showed a stimulatory effect on xylanase activity. The remaining activity was found to be 77%, 89%, and 92% in the presence of EDTA, 1,10-Phenanthroline monohydrate and beta-mercaptoethanol, respectively. In this study, some known purification materials were compared for effectiveness. According to the results, cellulase-free xylanase ASX42 has shown a stimulatory effect on germination of Anagyris foedita and Ceratonia siliqua seeds. It has also produced a whitening effect on wastepaper pulp.
Assessment of Redox Homeostasis Via Genotoxicity, Cytotoxicity, Apoptosis and Nrf-2 in Colorectal Cancer Cell Lines After Treatment With Ganoderma Lucidum Extract
(Taylor & Francis Ltd, 2024) Tuluce, Yasin; Keles, Ahmet Yasin; Kostekci, Sedat
This study aimed to investigate the cytotoxic and apoptotic effects of Ganoderma lucidum, Pleurotus ostreatus, Pleurotus eryngii, and Inonotus hispidus fungal extracts on HT-29 and HCT-116 colorectal cancer cell lines and to search the DNA damage and oxidative stress caused by these extracts. Accordingly, mushroom extracts were applied to colorectal cancer cell lines in vitro, and the IC50 result was obtained with the MTT test. According to the IC50 result, Ganoderma lucidum extract had the most effective cytotoxicity value among all used mushroom extracts. TAS, TOS, and NRF-2 tests were used to investigate the molecular effect of Ganoderma lucidum extract on oxidative stress; the DNA ladder test was performed to assess DNA damage, the Scratch assay method was applied for cell migration analysis, and the colony assay was used to determine the colony formation potential of the cells. The results showed that Ganoderma lucidum mushroom extract reduces cell proliferation, colony formation, and NRF-2, induces DNA damage, slows cell migration, and increases oxidative stress. This study shows that Ganoderma lucidum mushroom extract reduces cell proliferation through damaging cellular DNA and has a cytotoxic effect in colorectal cancer cell lines.
Design, Synthesis, and Evaluation of Pyrrolopyrazine-Substituted Benzoxazole/Benzothiazole Derivatives Targeting Aurora Kinase a in Mcf-7 Cells
(Wiley-V C H Verlag Gmbh, 2025) Kuzu, Burak; Kostekci, Sedat; Karakus, Fuat; Tuluce, Yasin
This study reports the synthesis, characterization, and biological evaluation of 19 benzoxazole/benzothiazole hybrids (19a-s). The compounds were synthesized through a multi-step process and structurally confirmed via NMR, elemental, and MS analyzes. Their antiproliferative effects were assessed on MCF-7 breast cancer and HME1 healthy epithelial cells. MTT assays identified 15 compounds with significant cytotoxic activity, among which 19e, 19g, 19i, 19j, and 19k exhibited high selectivity for MCF-7 cells. ELISA results demonstrated that 19g, 19i, 19j, and 19k significantly reduced AURKA protein levels in MCF-7 cells, while sparing healthy cells, suggesting their role in inhibiting cancer cell proliferation. These findings highlight 19g, 19i, 19j, and 19k as promising selective AURKA-targeted agents for breast cancer therapy.
Investigation of Potential Anti-Metastatic Effect of Metformin and Caffeic Acid Combination Therapy in Breast Cancer Cell Line in In-Vitro Culture Model
(Humana Press inc, 2025) Yavuz, Halil; Tuluce, Yasin; Karakus, Fuat; Kostekci, Sedat; Tuncyurekli, Merve; Keles, Ahmet Yasin
The invasion and metastasis of cancer cells transform localized cancers into systemic and life-threatening diseases, posing one of the most significant challenges in cancer treatment. This study tested the hypothesis that combined treatment with Caffeic acid (CA) and metformin (MTF) could inhibit or reduce effective signaling pathways involved in the proliferation, survival, and metastasis of MCF-7 breast cancer cells. Anti-proliferation analysis determined the IC50 values for MTF (4.5 mM) and CA (163 mu M) after 72 h. Cell migration analysis showed that MTF and CA significantly inhibited MCF-7 cell migration by the 72nd hour, both alone and in combination, without affecting HME1 healthy cell migration from the 48th hour. Colony formation analysis revealed that CA completely inhibited colony formation in MCF-7 cells, while MTF reduced it by 19%. ELISA results indicated that neither CA nor MTF affected the levels of VEGF-A, E-cadherin, or TINAGL-1 proteins, which are involved in MCF-7 cell migration and invasion. However, MTF significantly reduced IL-1 beta protein levels, and CA significantly reduced IL-4 protein levels in MCF-7 cells. RT-qPCR results largely supported the ELISA findings. Overall, CA and MTF exhibited potential to inhibit MCF-7 cell apoptosis, migration, tumor microenvironment modulation, and metastasis.
Investigation the Immunotherapeutic Potential of Mir-4477a Targeting Pd-1/Pd-l1 in Breast Cancer Cell Line Using a Cd8+ Co-Culture Model
(Springer, 2025) Tuluce, Yasin; Kostekci, Sedat; Karakus, Fuat; Keles, Ahmet Yasin; Tuncyurekli, Merve
BackgroundIn the present study, we investigated the immunotherapeutic and anticancer activities of microRNA-4477a (miR-4477a) as a PD-L1 inhibitor in breast cancer cells (MCF-7).MethodsTo this end, a series of analytical procedures were conducted, including bioinformatic analysis, RT-PCR analysis, PD-L1 ELISA, in vitro co-culture analysis, cytotoxicity assays, cell migration assays, and colony formation assays, with the objective of determining the anticancer activity of the compound in question.ResultsThe results demonstrated that miR-4477a can bind to three distinct regions of PD-L1 mRNA with high scores (94%, 88% and 80%), effectively targeting and suppressing the crucial regulatory pathways of cancer cells. In vitro studies demonstrated that a 25 nM dose of miR-4477a caused relatively high cytotoxicity in the MCF-7 cell line, suppressed PD-L1 gene expression, and decreased sPD-L1 protein levels, strongly inhibited cell migration, and significantly reduced colony formation. The in vitro co-culture analysis revealed that cancer cells were unable to evade the surveillance and cytotoxic activity of T cells (CD8+) due to the blockade of PD-L1 expression by miR-4477a.ConclusionsIn conclusion, miRNA-4477a has the capacity to regulate immune responses in breast cancer cells and may therefore be a promising candidate for use in cancer immunotherapy as a therapeutic agent.